Measuring instrument



June 11, 1946. w REYNOLDS Q 2,401,962

MEASURING INS TRUMEN T Filed April 8, 1943 INVEN TOR.

Patented June 11, 1946 'UNlT-ED srArss PATENT OFFICE MEASURIN 2 ZZ SZRUMEN T William Elmer Reynolds, Coquille, Oreg. Application April 8, 1943, Serial No. 482,305

This invention aims to provide a distancemeasuring device embodying novel means whereby an electron-ray tube of the visible indicator type-may be employed to give a visible signal when the parts of a pair of calipers, micrometer or the like, come into contact with an object, it being unnecessary to rely on the sense of touch.

It is within the province of the disclosure to improve generally and to enhance the utility of devices of that type to which the present invention appertains.

With the above and other objects in view, which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being understood that changes in the precise embodiment of the invention herein disclosed, may be made within the'scope of what i claimed, without departing from the spirit of the invention.

In the drawing, a single diagrammatic figure depicts a device constructed in accordance with the invention.

The numeral 9 marks the tail spindle of a lathe, and at 2 there appears a tubular object which is chucked at 3 upon th rotatable memher-4 of the lathe. Let it be supposed that it is desired to ascertain the diameter of the bore of the object shown at 2, although the device hereinafter described may be used for measuring other distances, and may be employed elsewhere than on a lathe.

A distance gauge is employed, and is shown as a pair of calipers comprising legs 5 and 6, made of conducting material, the leg 8 carrying insulation '4' at its working end. The distance gauge need not be a, pair of calipers and the calipers or its equivalent constitutes a portable switch. It may be any suitable instrument comprising relatively movable members capable of taking ofl a distance, the working part of one member being a conductor of electricity, and the working part of the other member being a non-conductor, such a description being broad enough to read on a micrometer gauge, for example.

' The drawing'shows an electron-ra tube 8 of the high-vacuum type and capable of indicating visibly the effect of change in the controlling voltage. For difi'erent controlling voltages, the shaded pattern produced on the fluorescent target 8 varies ordinarily through an arc of approximately ninety degrees. The extent of the shaded area is governed by the voltage on the ray-control electrode Ii, which is an extension of the connected, respectively, at

1 Claim. (Cl. 177-311) triode plate II that is disposed between the cathode i2 and the target 9.

The voltage on the ray-control electrode i0 is determined by the voltage applied tothe grid i 4 of the triode. A decrease in triode grid bias decreases the voltage on the ray-control electrode i0, and an increase produces an increased volt age on the ray-control electrode, The heater appears at l5.

The mains are indicated at l6 and i1 and are i8 and i9, with the pins of the heater i5. The mains supply, preferably a 110 volt current, D. C. or A. C. A conductor 20 is loined to the connection i9, and therefore to the main i l, the conductor having (diagrammatically considered) a'branch M for the target 9, and a branch 22 for the plate H,

A conductor 22' is jointed to the connection l9, and is grounded in any suitable way, for instance as shown at 23 on the lathe or other ma-' chine wherewith the device is used. The cathode i2 is joined at 2 3 to the conductor 22', and the grid M is joined at 25 thereto. A conductor 26 extends between the connection it and the conducting leg 5 of the calipers, or to some corresponding part of an instrument functioninglike a pair of calipers but difi'erlng structurally therefrom. The pins of the tube -8 of course operate in the usual way in bringing in the tube 30 properly.

The conductor i9 embodies a line load resistor 36, preferably of about 360 ohms. The branch 22 embodies a plate resistor 2'5 preferably of about one megohm, causing high potential on the plate ii. The conductor 25 embodies a resistor 28, and the conductor 22' embodies a resistor 29, the parts specified serving to bias grid negative sufllciently with respect to the cathode l2 so as to cut plate current, and the target 9 will show fluorescent throughout.

When the legs 5 and 6 of the calipers (if a pair of calipers happens to be the instrument selected) come into contact with the obJect 2, the grid it of the tube 8 is made positive with regard to the anode and the target 9, plate current flows, and a shadow appears on the target. The shadow comes on the-target 9 the instant that con-' 3 some of the A. C. ripple and causes the tube 6 to operate with a clear-cut shadow.

What is claimed is: a A tube and tube-circuit structure for use in making pressureless micrometric measurements. including a tube comprising a, heater, a cathode, a grid, a triode plate having an extension forming a ray-control electrode, and a target, an electrical circuit including the heater and including aground forming one side of the circuit, a connection between the plate and said circuit, a connection between the circuit and the cathode, a connection between the circuit and the grid, the

accuses two last-specified connections having resistances of such degree as to bias grid negative sufllcient- 1y with respect to the cathode so as to cut plate current and to cause the target to show fluorescent throughout and a portable switch comprising electrically connected relatively movable members for engagement with spaced portion of the ground, one of said members being a conductor, and the other of said members being an insulator, one of said -members forming the other side of the circuit.

WILLIAM ELMER REYNOLDS. 

